With an acre and a half I think would be looking at a larger unit if it's in your budget. I use a 445 on a slightly smaller property and it still takes an hour and a half to get the lawn mowed. It doesn't sound like a lot of time, but when you have to do it every 4 days it cuts into time available for other things. I do only have a 48" deck which I now wish was larger. When we built the house there were 23 more trees on the property than there are today. At that time I needed the smaller deck to get between some of them. Now that they're gone I could probably do the job in a bit less time with a larger mower.
The nice thing about the 445 is that it has a 22 hp fuel injected WATER COOLED engine. The tractor is 18 years old and the only maintenance so far has been oil and transmission fluid changes, a couple tune ups, and a new battery. I purchased this unit mainly because of the quality and the fact that John Deere still stocks parts for the first garden tractors they built in 1966. Even at 18 years old the deck looks like new. I must admit I do remove it every fall and pressure wash it.
To put things in perspective I made a spread sheet with over a dozen different brands when I was looking for a new tractor. At first John Deere wasn't even on the list, mainly because of price. After I started lining out all the options I needed the other tractors started to rapidly climb in price. When all was said and done the JD was less expensive than several other brands. The final decision was based on the availability of parts.